Solution-state interactions of Bis(pentamethylcyclopentadienyl)ytterbium, Cp2Yb, with trialkylphosphines and R3PX complexes (X = O, NR′, CHR″)

Article abstract of DOI:10.1021/om00009a039

The interactions formed between Cp^*₂Yb (1) and phosphines and R₃PX derivatives (X = O, NR', CHR″) in solution have been investigated using multinuclear (¹H, ¹³C, ³¹P, ¹⁷¹Yb) and variable-temperature NMR spectroscopy. Adducts of 1 with Me₃PO and Et₃PNH undergo slow intermolecular exchange in solution at 25°C (NMR time scale); both 1:1 adducts (Cp^*₂Yb(OPMe₃), 7; Cp^*₂Yb(HNPEt₃), 9 and 1:2 adducts (Cp^*₂Yb(OPMe₃)₂, 8; Cp^*₂Yb(HNPEt₃)₂, 10 have been isolated. The spectroscopic properties of two ylide adducts, Cp^*₂Yb(Me₂PhPCHSiMe₃) (12) and Cp^*₂Yb(Me₂PhPCH₂) (13), have also been investigated. Intermolecular exchange can be slowed at low temperature in both cases; in the former complex a second process, resulting in inequivalent Cp^* rings and inequivalent P-bound methyl groups, can also be slowed at lower temperatures. The nature of this process is discussed in detail. The solid-state structure of 12 has been determined. The NMR values for all of the complexes are discussed in detail. In addition, the '¹⁷¹Yb chemical shifts for 6, 7, and 12 have been measured, via ¹H/¹⁷¹Yb indirect detection utilizing long-range J_YbH coupling, and are discussed.